Rotary cutting tool



Fel 13 1945.. H. F. BAKEwL-l. V2,369,273

`ROTARY CUTTING TooL Filed March 23. 1943 4 Sheets-Shee'rl 1 www ATTORNEY.

Fbf 113 1945- l F. BAkEwELL 2,369,273

ROTARY CUTTING TOOL Y Fiied Haren 25. 1943 4 sheets-smelt 2 /Zfy'l' 16 33 f7 35 ff ATTORNEY.

Feb. 13, 1945. H. F. BAKEwELL 2,369,273

' ROTARY CUTTING TOOL Filed March 23, 1943 4 Sheets-Sheet 3V w'j" f3.

55@ 571 rieb 57a 53 560 Feb. 13, `1945 H. F. BAKEwELL 2,369,273

ROTARY CUTTING TOOL Filed March 23, 1943 4 Sheets-Sheetl Y 7o @j t ma w46.

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26a 105 www v ATTORNEY thusl effecting a tremendoussaving engagement between the shank Patented Feb. 13, 1945 A UNITED STATES PATENT: ortica l l v a noranrzt'srzrve 'rooL ,y

i i F. Bakew'eu, san Marino, cant. Application Mai-cn 2s, 1943; sensi No. 480,231, `nomma. iol. 11i-14o) This 'invention relates .to rotary cutting tools,

and particularly to tools of this class in which a cutting member is removably mounted on a shank ior rotativefengagement with the work. The tool may be rotated and the work held in fixed position, or the tool may be held xed and the work rotated. The term rotary cutting toolin accordingly used herein t designate a tool that performs a cutting operation by relative rotating engagement between the tool and the work,and without limitation toirotation of the tool itself.

Tools of this type may be used for various purposes, the cutting member employed being one that is adapted to perform the desired operation ly secured to the shank and accurately centered and aimed with respect thereto. l

A further object of the invention is to provide lng -shoulders that are located inward from the periphery of the cutting member andare ac- Y curately formed so as to provide simultaneous `and positive driving engagement between the shank and the tap at a plurality of circumfer- `entially spaced positions, whereby the force required to drive the cutting member is distributed and excessive concentration of pressure is avoid- A further object is to provide a construction having the abovementioned advantages, and in which relatively simple operations may beV employed in forming the interengaging parts with the accuracyrequired to ensure correct positioningV of the .cutting member and simultaneous engagement 4of the respective driving shoulders.

Another object is to provide a tool of this type whose construction is such that adequate strength is'provided to resist stresses produced in the tool during use, even at high speeds of opl eration;V and even with cutting members of relatively small diameter.

` on the work, such as a tap for internally threadl A further object. is to provide a construction in which the interengaging driving means on the shank and the cutting member are held securely in rigid engagement with each other'so as to resist rotation of the cutting member relative `to the shank in both directions of such relative rotation.

Another object of the invention is to provide a tool of the type above described in which the cutting member may be made reversible on the shank, that is, it Amay' be secured tothe shank a tool of this type in which the cutting member Y and shank are provided with interengaging driv-l with either end disposed forwardly for initial engagement with the work, andprovided with cutting elements located and formed for proper cut- .ting engagement with the workwh'en mounted in either of these two positions, so that when the cutting elements that engage the work whenA the cutting member is in one position become worn, the cutting member maysimply be removed 1 and reversed and fresh cutting' elements made ed.. while at the same timeA 'avoiding interference with the cutting operation or weakening of*v the tool adjacent the cutting edges.

Numerous advantages are obtained b y the use of a toolhaving a removablecutting member,

because only the cutting member itself need be made of the required high. speed alloy steel. When the cutting member is worn out, it may be replaced by a new member onv the same shank,

in consumption of special alloy steel.

Furthermore, cutting membersl of diierent types4 or sizes `may be'used interchangeably on a single shank. By means of my improved conavailable.

Another object is to provide a construction in which a pilot membermay be secured to the shank, projecting forwardly beyond the cutting member for guiding the tool relative to the work. A particular object in this case is toprovide for utilizing the pilot member to secure the removable cutting member to the shank.

Another object is to provide a construction in which multiple cutting members of progressively increasing working diameters may be removably lmounted on the-same shank and secured lthereto in properly alinedand centered relation and in positive'driving engagement therewith, whereby the desired 'cutting may be done partly bythe iirst cutter and completed by a succeeding cutter. Inthis connection, a plurality of cutting members of differentl `types may be so mounted in order to perform diiferent cutting Steps in a ber and without appreciable' wear due to driving and thecutting single operation with the same tool. As a specinc example, a reamer and vatap may be used 'infthis manner to ream and tap a parent in elevation, of a multiple-tap tool;

operation. As lanother example, I may use' a combinatlon of drill and tap, to drill and tap a hole with the same tool. In either .of these cases, the first cutting member is one that cuts a smooth cylindrical bore, while the second is a threading tool.

tion will be pointed out hereinafter or will be apfrom the' following description.

The accompanying drawings illustrate rotary cutting tools in accordance with my invention, and referring thereto:

Fig. 1 is a longitudinal vertical section, partly in elevation, of a tapping tool provided with a single removable tap member;

Fig. 2 is an end view thereof looking toward the left in Fig. 1;

Fig. 3 is a transverse Fis. 1:

Fig. 4 is a partly shank shown in Fig. 1i" Fig. 5 is an end view of the shank looking toward the left in Fig. 4;

Fig. 6 is a lonigtudinal vertical section, partly section on line 3-3 in sectional side elevation of the Fis. 'l is a transverse section on line 1-I4 in Fig. 6: v Fig. 8 is a partly sectional side elevation of the driving sleeve connecting the two -tan members in-Fig'aand 7; rw

Fig. 9 is an'end view of said driving sleeve;

Fig. 10 is a partly sectional side elevation of a tapping tool similar to that shown in Fig. 1, provided with a pilot member of maximum diameter;

Fig. 11 is a partial view similar to Fig. 10 showing a pilot member of smaller diameter;

. aseaavs Further objects andy advantages of the invenfrom that end. The outerf'feee s er the aange provides an annular outwardly' projecting shoulder against which one end of thecutting member Il bears when-mounted on the shank, as shown at 1 in Fig. 1. The face or shoulder 8 is machined to coniorm accurately to a surface of revolution about the axis of the shank, and preferably to a plane surface perpendicular to said axis. When' the invention is embodied in the construction shown in, Fig. l, between shoulder 6 and cylindrical portion 4, the extension 2 ofv shank l is provided with a driving portion Il of hexagonal or other polygonal external shape.

longitudinally extending,

The faces of said polygonal driving portion are preferablyv disposed wholly outward with respect to the periphery of the cylindrical portion 4, thus providing a plurality of circumferentially spaced,

Vject outwardly beyond the portion 8 may be scribed about a circle whose radius is at least equal to, and preferably somewhat greater than,

the radius of cylindrical portionl.

Shank I is further provided with sere lo extending iongitudmtuy thereof, from thetap-receiving end,

. ing the cutting member in position, as described Fig. 12 is e side elevation, partly in section, of

a reaming tool provided with a removable shell reamer;

Fig. 13 is an end view thereof, looking toward the left in Fig. 12;

Fig. 14 is a side elevation of a multiple-reenter tool; I l Fig. l5 is a sideelevation of;a combined reaming and tapping toon Fig. 16 is a partly sectional side elevation of' a combined drilling and tapping tool;

Fig..l7 is a view showing a modiiled'constructiene: e tapping tool, the shank being snows in elevation and the other parts in section;

Fig. 18 is an end view thereof looking toward the left in Fig. 17:

Fig. l9'is a transverse vsection on line l--It in Fig. 17:

Fig'. 20 shows a modified construction of a multiple-tap tool. the.V shank being shown in elevation and the other parts in section: and

Illig. 2l isa longitudinal section showing an- Y other modification of the invention, as' applied to- `afmultiple-tap tool,- the shank being shown partly in elevation.

Referringto Figs. l tuoy 5,1 have shown a'iool comprising a shank l. e cutting member u are;` movably mounted on a portion or extension of the shank indicated generally `at 2, adiacent one *end thereof. and a threaded retaining member such as screwl 2l securing the cutting member to shank. adiacent' the other end. as indieatediet -3,.i s formed to fit 70 the shank. 'The portion of the within a chuck for rotating the tool, and may be either taperedorstraight, as desired.

" Asbest shown in Figs. 4 'and 5, the shank is provided with a cylindrical. portion, d .extending a short distance from the tap-receiving end, and

' shoulder 8'. v with an `niarange. dat a position removed i@ sha-nis hereinafter.

The cutting member II is'of generally annular shape, and is shown as a shell tap provided with external threads I3 for use in cutting internal threads. The tap is provided witha plurality of alternate flutes .I4 and threaded lands l5.`

The tap is shown as provided with a centrally 'located cylindrical bore I8 which is accurately machined to make a close nt with`the cylindrical portion 4 of the shank, said bore being formed in accurate coaxial relation to the circumferf provide adjacent each end of 'the tap a set of circumferentially spaced inwardly proiectinglqgitudinaily extending shoulders i9, each set co" prising a plurality of such shoulders corresponding to the outwardly projecting shoulders 9. of -l the shank-and so .positioned that all of the shoulfdersl of one set are simultaneouslyin close en gagement `with they respective-shoulders lil when the tapis mounted on theshank. The internal cross-sectioned shape of each of these recessed portionsv of the tap may be described as a polygon circimscribed about a circle whose radius is at least equal to that of cylindrical bore I6, and

preferably somewhat'greater'in order to provide a continuous annular shoulder I8 whose minimum radial width (see Fig. 2) is such as to provide an adequate surface for engagement by the headof screw; 2|.

- The screw 2i is screwed tightly inthreaded bore f Y It, the heacLof said screw bearing `ag st the forwardly vdisposed shoulder VI 8 of the tap and holding the rearend face of the tap firmly against fits closely within the bore IBof the tap shoulders 8 that proy peripheryl of said portion 4. The external cross-sectional shape of described as a polygon circumcenter the tap relative to the axis of The cylindrical portion 4 -of the and serves to support and center the tap on the shank'. l

The tap Il is-shown'as adapted to be mounted reversibly on the shank, withl either end thereof in engagement with shoulder 6, the other end of the tap fbeingin either case disposed at the forward end' of the tool for' initial engagement with the-work. Each end voi the tap is accordingly shaped to conform closely to the surface of shoulder 8, so as to maintain the tap -in accurate alinement with the shank. 'Ihe tap 1 is also shown' as chamfered at each endin wellknown manner, as at 22', to facilitate engagement of the threads with the work in `either position of the tap. Adjacent each 4end of the tap, the threads are'formed to provide cutting teeth at Vthe leading edges of the lands in the direction of rotation' relative to the work when v 7, two shell tap members Ila, 'and IIb lare respectively."

that end isjin 4position to initially 'engage the4 work, and it will be appreciated that these cutting teeth are disposed at opposite edges of the lands -adjacent the respective ends of the tap Furthermore, if desired the -thre'ads may be undercut at'the leading edges ofethe `lands in the direction of such relative rotation, and may be back-relieved toward the trailing edges' in well-known manner, such -undercutting and back-relieving being also oppositely arranged adjacent the respective ends of the tool.`

'I'he direction of rotation of the tap relative to the work, for cutting right-hand threads, is indicated 'by the.arrow at A in Fig.2. Upon 'rotation of the shank in thatV direction, with the tap mounted either in the .position shown or in the reverse position on the shank, the

. several outwardly extending :shoulders 9 onv the driving portion 8 of the shank engage the rel spectve inwardly extending shoulders I9 of thfI set adjacent' the end of the tap which is at .that -time disposed. rearwardly with referencevto the work. Thus. the driving force required to be tra'nsmittedfrom the shankA tothe tap is l l distributed. over the entire areas of these venseeing shoulders.

The-recesses I1 ofthe tap are shown as being Y of -somewhat greater. axial length' than the polygonal portion 8-of the shank, so that when l either end ofthe tap engages shoulder 8 of the shank the rearwardly disposed shoulder I8 is spaced somewhat fromv 'the shoulder 23A at theforward end ofgsaid polygonal portion. .II desired, howeiger,l these .recesses may be maderoi less axial length so thatl said. shoulders i8v and 23 may befbrpught into abutting relation in ad .dition to. Vor .instead of, bringing the end ot the tap into engagement with shoulder -1, for

properly alining the `,tap on the shank.' I

'It.will be vseen that the polygonal driving portion'. 8 of the shank' provides a plurality of salient angular projections that` extend .longitudinally4 of the shank. These angular projections nt snugly within a` plurality' of correspondingly shaped Ireentrantangular portions in one or the other -of thel recesses l1 of .the

tap, so as to provide drm positive. driving engagement between' the ,faces of the driving porf tion 8 and recess l1 at both-the. leading and trailingsides of each angle in the normal direction of rotation of the tool. This construction is of advantage in preventing any rotation of the tap relative to' the shank, in either direction of such relative rotation. VThis is par--` ti'cularly `advantageous for use on .certain types m of machines in which-it is required that,.in ro'- tatin'g the tap in the reverse direction for remounted in successive positions longitudinally of the shank 26. 'I'he cutting threads of tap member Ila mounted at the forward end of the' 'lhe shank` 26 is similar to the above described shank l, except that the cylindrical portion la extends entirely through the rearwardly disposed -tap member Hb and is of suiiicient length' to projectinto theforward .tap member lla and through the majorportion of the length of cylindrioaljbore l6a thereof. The shank is provided as before withan outwardly extending an-l nular shoulder Ea and with a, driving portion 8a of hexagonal or other polygonal shape, 'between the shoulder 6a and cylindrical portion 4a. Other parts of the shank are designated by the same reference numbers as in the first de- `scribed.form with the addition of th-e letter a.

A relatively thin spacing member or washer 30 ispreferablyprovided between the two tap members, and is provided with` fiat end faces bearing against the rear end of tap Ho and the forward end of tapv IIb. Said `spacing member is 'of less diameter than the tap, so that, when the parts are assembled on 'the shank, a-short space is provided between thfl two taps as indicated at 33 in Fig. 6 in order to facilitate the escape of lchips produced by the cutting teeth at the forward end of tap member Hb.

A driving sleeve 21 i's provided, fitting around the cylindrical shank portion 4a, and extending' u' central opening in spacing member 30.

'I'he driving sleeve 21 is s ho'wn more fullyin Figs. 8 andi). It isl provided with a cylindrical bore 28 fitting slidably laround the cylindrical .portion la of the shank and preferably in close engagement therewith, and its outer :face Vis of hexagonal or other polygonal shape corresponding to,` and, formed accurately forclose driving.

engagement with, the recesses IIa and [1b in the respective tapmembers. Thus, said driving4 sleeve is provided with a plurality of outwardly` projecting shoulders`.29 in simultaneous close driving engagement with inwardly projecting "shoulders 3| in the forwardly disposed' polygonal recess llb of tap IIb, and with aplurality of outwardly projecting shoulders l2 in simultaneous close driving vengagement with the inwardly proiecting shoulders |911 in the rearwardlydisposed.4

4recess |1a oftap member Ha. j The length of driving sleeve `.2 1 is preferably such as to extend through the major portion of thelength of the recessed` portions l1aand ilb' ofthe two tap members, the ends thereof being' preferably spaced somewhat from :the shoulders Ila and IIb ofthe respective taps, as showi in Fig. `(i.`

A- retaining screw :la is secured inthreaded bore |0a of. the shank. The head .of said screw -larly close driving engagement with the taps, as de scribed above.y Thus, rotative driving force is transmitted from the driving shoulders of the shank to tap lib, and thence through driving` sleeve 21 to tap lla.`

When two taps are thus used for making a. rough cut and a finishing cut in producing e. set of internal threads, the cutting threads of the two taps should be ground in pairs, and when so ground, can not be reversed on the'shank as described above in connection with the single tap.

aseaavs However, where tough high carbon steel is being tapped it is a decided advantage to combine both the roughing and finishing taps in a single tool, particularly when used on a tapping ymachine having a lead screw feed, which greatly enhances the life of the tap and often permits tapping successfully where it Conni not be done otherwise.

Figs. 10 and ll illustrate the use of pilot memvmrs for guiding the tool in cases where it is necessary that the thread formed by the tap be `formed accurately in concentric .relation to. a

bore in the work. In these figures, the construction of shank i and tap member li is thesame as shown in Figs. l through-ii, and the mounting of the tap on the shank is also the same except that the threaded retaining member is provided with a head portion formedas a pilot extensionprojecting forwardly beyond the' tap for engagee ment with a preformed bore in the work."

In Fig. 10 the pilot. member 36 comprises a' cylindrical pilot head or extension el of approximately the maximum diameter that can be used with the tap diameter shown, and a coaxially disposed threaded stem 3B engaging threaded bore it of the shank, `whereby the pilot extension is spaced vlands 5l' whichD mayk be either straight or helical and either parallel or tapered. The lands are chamiered` at bothends as at 58 and are provided with suitably shaped cutting edges Us arranged oppositely at'the portions adjacent the respective ends thereof, said cutting edges at each end being at the leading edges in the direction of rotation (indicated by the arrow at A in Fig. 13).

when that end is disposed engaging the work.'

lBeamer 5l is also provided forwardly for initially with a centrally located cylindrical'bore 6l tting closely the cy.- lindrical portion 53 of the shank, with a centrally located'recess 62 at each end of hexagonal or other polygonalshape; formed accurately for. engagement with the driving/ portion 55 of the shank, and with outwardly extending annular shoulders B3 at the inner, ends of said recesses.

'I'he relative -arrangex'nentvand functions .of these parts and of the coacti'ng parts of the shank are. t l the same as in' Figs.'1 to 5, except that the cylindrical portion 53'and bore Si are of somewhat greater length, the'reamer being rshown as relatively longer than-the tap member of Fig. 1. As

beforethe reamer 5I is secured in position on the shank by means of Iscrew 6d whose head engages the forwardly disposed shoulder S3 and maintains the rearward end of the reamer in engagement with shoulder` 5d' -on the shank.

It will be apparent that reamer di is reversible on the shank in the manner describedabove, and

is'adapted for cutting engagement with the work whenmounted in either of the two positions. i Pilot memberaas. illustrated in Figs. 1U and il,

may .also be-employed in conjunction with the above described reamer, and may in this case be similarly used to secure the reamer tothe shank.

accurately centered with respect to the' tap. The

cylindrical pilot portion 3l is slotted atits forward end, as at 30, for rotation by a screwdriver.

or the like, and is provided at its rearward end with an annular shoulder 6l formed as asurface of revolution, which engages the'forward end of tap ll to hold said tap securely in position on the shank and ensure proper alinernent of the pilot Fig. 14show's a multiple-seamen' tool. comprising two shell reamers Ela and elle mounted in successive positions onshank; 52a. The forwardly disposed reamer @la is of smaller' diam#`4 eter than reamer Bib, whereby the tworeamers are yadapted ,to make roughing and finish cutst respectivelnor making multiple machining operations. The construction-of each rcamer is the same as in Figs. 12 and 13. The construction of shank 52a andthe mounting of the reamers relative to the shank and tap. The pilot member is also shown as provided with a cylindrical portion lf2 extending within the polygonal recess il at the forward end of the tap.

In Fig. 1l the pilot member 6 is similar tothe member- 36 in Fig. 10, except that the for-v wardly projecting pilot extension B5 is of-smaller thereon are the same as in the. multiple tap tool shown in Figs. 6 and 7, except for :inference in length. of certain parts due tothe greater rela- .tive length of the reamers. The cylindrical por-v tion 53a of the shank extends through the rearward reamer Sib' and' through. the major portion of the ycylindrical bore -la of the forward reamer,

. and` driving connectionbetween the two reamers is again provided by means offs. hexagonal driving sleeve 6l which is similar in construction and 1 diameter for engaging a smaller bore in the work, 1 Y

and 'is provided with a ange portion t8 extending within recess Il in the tap il, said flange being of greater diameter than the cylindrical bore I6 of the tap and bearing against the for-.-

wardly disposed shoulder I8 to secure thel tap. firmly in position on the shank in the saine manner as the head of screw 2| in Fig. 1.

In the reaming tool shown in Fis removably mounted on shank EL Said shank is similar to shank I above described, being simiprovided with a cylindrical portion 53, an

annular flange 5I 'providing an outwardly extendfunction to the sleeve 21 shown in Figs. 8 and 9.

Said sieeveis held' in driving engagement with the driving shoulders within the rearwardlyand ing shoulder Il', a hexagonal or'other polygonal divingv portion 55. and a central ythrcaded'bore Tm reamer Bl is provided Iwitha pluralityof the. shank' rearwardlyof their-earner. The effeci2 and 13, v Athe cutting member M is, formed as a shellsreamer forwardly disposed polygonal recesses of the respective reamers Bla and Bib, and screw 64a engages threadcd bore 56a inthe shank to secure the reamers inpositi'onon the shank, a suitable spacing member 88 being preferably provided between the two reamers', all in the same manner as shown in Figs. 6 and "1..

Other combinationsof cutting members may valso'be used. For example, Fig. .15,.shows a shell reaxncr lic mounted "on the forward end portion` oi'. a' shank 52e, and a shell tap' llc mountedon tive" diameter of the-rcamer is about equal to or slightlyv less than the-minordiameter'of the tap.'

connection between the tap land the reamer aaeaavs vwhereby the tool is .adaptedto perform a com reamer. The tool'also comprised-.as before, a 1

hexagonal driving sleeve 61e, providing a driving and. a screw Glo for securing the 'two cutting niem- 'bers in. position on the shank, with a spacing member 98e therebetween. A'combined drilling and tapping tool is shown in Fig. 16, comprising a shank 1I, a shell tap 12' removably mounted thereon.' and adrill member removably secured to the shank forwardly 'of the tap and serving as the means for securing the tap' to the shank. Shank 1I is provided with a flange 13, a hexagonal or other polygonal driv` ing portion 14, and a cylindrical portion 15, simiy lar to the corresponding parts of shank I in Fig. l, yexceptl that the cylindrical portion' 15 is of greater length and is shown as extendingV somewhat beyond the forward end ofthe tap. Said shank is also shown as provided at its forward end with an externally duced diameter.

The construction of tap 12 andthe relation thereof to ,the shank arev the same as shown in Fig. 1 or in Fig. 15,' said tap being provided as before'with a hexagonal or polygonal recess 11 at each end and a cylindrical bore 18 engaging cylindrical portion of the shank.

The drill member 10 is shown as provided with spiralV lands 19 and flutes. 8|, the forward end thereof being formed as a'drill point 82 of any usual or suitable shape. providing a suitably. in

tapered forward end portion of each land. The diameter of drill 10 is aboute'qual to-or slightly less than the minor diameter of 'the tap. The

rear portion 84 of the drill is shown as being cylindrical in shape and provided'with a rearwardly projecting annular shoulder portion 85 rbearing against the forward en'd of the tap, and with a.4`

hollow cylindrical .coaxial sleeve portion 86 of reduced diameter, `also extending rearwardly r therefrom and adapted to t within the forwardly disposed recess 11 of the tap and to ilt'slidfwably around and in 'close engagementl withI the a Spanner wrench or other suitable tool. It will threaded portion 16 of re-- l The operation ofl the combination tools sho the tool is moved forwardly in rotative cutting engagement' with A,the work, the reamer'member 5|.c or the drill 'member -loxflrst cutsasrnooth cylindrical boreand the associated tap member then enters and threads such'bore.A v

Various modifications maybe made. Vin 'the :16.-

rnents-of'the tool .within the scope of'v this invention. For example, .as shown in Figs. 1''t119,v

the' removable cutting member such as 'shelltap 9| may: be provided with a central hole '92 of hexagonal or other 'polygonal shape extending coaxially therethroughy from one end to the other and providing, .as before,.a plurality of circumferentially. spaced inwardly projecting longitudinally extending l shoulders at positions adjacent each 'end of the tap. Such a hole may j beformedaccurately by a vsimple broaching op# clined cutting .edge 83. at the leading edge of the eration. rl'he` tap .is also shown as'recessedout-V wardlyfor a vshort distance from'each end, to vform cylindrical .recesses 93v extending 'outward beyond the periphery of hole 92 so as to provide annular outwardly extending shoulders 94 at the' inner ends ofthe respective recesses. The shank 96 is `providedzas "before with 'a flange 91, a'rhexagonal or other polygonal shaped driving portion Sformed to provide' a plurality ofshoulders for close driving engagementwith. :the Walls of hole 92, anda cylindrical 'portion-99 of reduced diameter disposed forwardly of por- -tion 98'. The -driving portion 98 'is of suii'icient4 length to extend through the rearwardly disposed recess 93'a'nd fons substantial distance within the hole 92, so'.' as to provide adequatel v interengaging.

driving engagement between the shoulders the same manner described above.` Asleeveorbushing member IIlI fits closely but removably around the cylindricalportion 93`of the shank, with-*its .outer surface ilttin'g closely within the forward' portion ofhole 9 2. so 'as to Vcenter and supportthe tap on theshank. TheA exterior surface of' this-sleeve is shown as being of hexagonal or other polygonal shape conforming with that ofA hole 92, but said sleeve -mayif desired have a cylindrical outer surface bearing against the Walls of said hole; As 'will 'be apparent, the tap is reversible, as before, and-.maybe mounted on the shank with either end disposed forwardly and with the shoulders of driving por- .tion 98 in rotative driving engagement with the shoulders of hole 92 .at a position adjacent the other end of the tap. Anotherpossible .modiflcation is to make the polygonaldriving portion 98 .of the shank of sufficient length to extend through the major portion of the length 'of hole f 92, whereby said'portion 99 'will itself serve to firmly support and center thetap,` andthe sleeve ql homered.

The. tap manif desired, be secured-tothe l shank in the same manner as inFlg. 1. Howbe noted that the' specific securing' means 1B and thosetwogeneral'types of securing means or with other suitable means for securing to thev shank the member which inturn secures the annularly shaped cutting member in position on the shank.

ever, I have shown in this case securing means of the same general type asin Fig. 16, comprising a threaded nut ,I021engaging'a short threaded extensionv |03 at the forward endof the shank.

'Saidnut |02 may be of circular shape'and provided with slots |04 for rotationthe'reof by a suitable tool.l Nut |042 is adapted-to ententhe forwardly disposed recess 93 and to engage shoulder 94 to hold the tap' securely o'nthe shank and in engagement with flange 91.

Fig. 20 illustrates the application of this same -type of construction in a multiple-tap' tool. '-'I'he relative arrangement and .proportions of the two in Figs. 1 5 and 16 is believed to be obvious. AsV

. y l acsasvsl shell taps flc and Bib-are the same as in Fig. 6.

4 while the construction of each tap is similar to Fig. 17,v with the addition or the letter a.. The

sleeve or bushing member ila is of the ,same cross-sectiona1 shape as the bushing member tot in Fig. 17 and extends around the cylindrical portion 99a of the shank, with its exterior surface in close driving engagement with. the polyg onal surfaces of holes 82d and 82h in the respective tap members. Said sleeve or bushing member serves not only to center and support both tap members on the shank but also performs the same function as the driving sleeve 2l in Fig. 6, namely, to transmit rotative driving force' from ltap member aib to tap member Qld. .as beiore, the taps are secured in position by means oi nut lara., a.V suitable ular spacing member loe being provided between the two tap members. Said spacing member is similar in shape and function to the spacing member d@ in Fig. f6.

It will be apparent that securing means such -as shownin Fig. 6 could, if desired be substituted for th'enut 402e the externally threaded extension w3c shown in Fig. 2d. Furthermore,

lit win be apparent that the moulded construe- 'tions shown in Figs. 17 to 19 'and in Fig. 2i) may be .applied respectively to a reaming tool as shown in Figs. 12 and 13 and a multiplev reamertool such `as shown in Fig. 1d. These constructions may also be used in connection with pilot members such as shown in Figs. l and ll, with combination reaining and tapping tools as shown in Fig. 15 or combination drilling and tapping tools such as shown in Fig, l6.

In all. of thetools descri led above, the interengaging hexagonal or polygonal driving portions are shown as extending parallel to the axis of the tool. This is not essential however, and ii desired these polygonal driving portions may be tapered longitudinally and still provide the desired rotative drivingf engagement. For. example, in Flgl the polygonal recesses Il or the tap member may be tapered or ared outwardly toward each en'd of the tap. AAs 'another example. the driving portion on-the shank, and the driving portions of the drivingl sleeve in tools having multiple cutting members may be taperedlongitudinally. trated in Fig. 21. which is similar to Fig. 6. except that the hexagonal or polygonal driving portion Ille of the'shank is tapered inwardly-toward the This latter modification is illusf forward end o! the shank, and the driving sleeve |09 is tapered inwardlyfrom' the' middle toward each end. The hexagonal or polygonal recesses Hl in the tap' members are shown as being parallel to the axis, and held by screw I I2 in driving engagement with the tapered portions its and Iclaim: 1. In a rotary tting tool, the combination comprising: a shank having a cylindrical portion and a driving portiomsaid driving portion being formed externally to provide a.l plurality oi' cincumferentially spaced outwardly projecting longitudinally 'extending shoulders: a cutting member removably mounted on said vin a position around said cylindrical anddriving pori tions of said shank, said cutting member being Y formed internally to provide a plurality of circumferentially spaced inwardly projecting longitudinally extending shoulders in close rotative driving engagement with the respective shoulders on the driving portion of said shank, and said cutting member being also providedwith a ceri` trally located cylindrical bore engaging closely 10 the cylindrical portion oi' the shank; and means securing said cutting member to said shankvwith the parts in engagement as above set forth.

2. `The construction set forth in claim 1, said cutting member being of symmetrical construction in an axial direction! whereby it may be mounted removably upon said shank with either end disposed forwardly for initially engagingthe work, said cutting membery being provided with a plurality of circumferentially spaced inwardly directed longitudinally extending shoulders adapted for engagement with the shoulders of said shank when. said` cutting member is mounted with either end disposed forwardly.

\ 3. In a rotary cutting tool, the combination comprising: a shanhhaving a cylindrical portion adjacent one end and a driving' portion located rearwardly of said cylindrical portion, said drivlng portion being formed externally to provide a plurality of circumierentlally spaced outwardly 8d projecting longitudinally extending shoulders; a

-cutting member removably mounted. on said shank with its rearward portion surrounding said driving portion and its forward portion surroundcing said cylindrical portion of the shank. said 8d rearward portion of. the cutting member being formed internally te provide' a plurality of vcircumferentially spaced inwardly projecting longitudinally extending shoulders. in close rotative drivingengagement with the respective shoul i@ ders on the driving portion of said shank; and

means securing said cutting member to said shank and supporting said cutting member in coaxial alined position with respect to said cylind'riearporuon of the shank.

e. The construction set forth lin claim 3, the forward portion of saldcutting member being provided-with a portion formedinternally to prgvide a plurality of clrcumferentially spaced in- 59-wardly directed longitudinally extending shoulf ders corresponding in dimensions and relative placement to the shoulders provided at said rearward end or said cutting member, whereby said cutting member is adapted for mounting on said .55 shank with either end of said cutting member dispd'sed forwardly for initially engaging the work and the shoulders at the other end of said cutting member in engagement with the shoulders onsaidshanlr.

go 5. In. a rotary cutting tool, the combination combination comprising: a-shank having a cylindrical portion adjacent one end and a driving portiony located rearwardly of said cylindrical portion and formed to provide a plurality of cir- 65. cumferentially spaced longitudinally extending shoulders that project outwardly beyond the periphery of said cylindrical portiOm-ad 'means removably mounted on said shankand provided with peripherallyldisposed cutting ele- 7 ments, with a plurality of circumferentially spaced inwardly projecting longitudinally extending shoulders in close driving engagement with the respective 'shoulders o! the shank, and

with a centrally located cylindrical boreenss ing closely the cylindrical portion of the shank.

. -ierentially spaced inwardly projecting longitudinally extending shoulders corresponding to, and positioned foi-simultaneous close driving engagement with, the respective shoulders of the shank, and a cylindrical centrally located bore engaging closely the cylindrical portion off the shank; and means securing said cutting member to said shank with the parts in engagement as above set forth.

7. In a rotary cutting tool, the combination comprising: a shank having a cylindrical portion adjacent one end arid-a driving portion located rearwardly of said cylindricalportion and formed to provide a plurality of circumferentially spaced outwardly projecting longitudinally extending shoulders; a cutting member removably mounted on said shank around said `driving and cylindrical portions thereof, said cutting member having-a central hole extending therethrough and formed to provide a plurality of circumferentially spaced inwardly projecting longitudinally extending shoulders in close driv ing engagement with the respective shoulders of the shank andspaced outwardly from the cylin` drical portion of the shank; anda sleeve disposed between and in close engagement with the cutting member and the cylindrical portionof the shank.

jecting longitudinally extending shoulders in close l driving engagement with the respective shoulders ofthe shank, anda sleeve member removably mounted on said shank and in rotative driving engagement with said rearward cutting member and the adjacent cutting member, whereby rota'- tive driving force is transmitted from the shank through said rearward cutting member and said sleeve to said adjacent cutting memberI` 10. In a rotary cutting tool, the Vcombination comprising: a shank havinga portion of polygonal external shape and a cylindrical portion of reduced diameter extending forwardly from said polygonal portion; a driving sleeve fltting closely around the cylindrical portion of the shank and having an exteriorsurface of polygonal shape;

and two cutting membersremovably mounted onsaid shank in successive positions longitudinally thereof, the rearward one of said cutting mein-I bers having a portion of polygonal internal shape tting closely around the polygonal portion-ofl onal external shape tapered' inwardly toward 8. A cutting member for rotary cutting tools, I

adapted to be removably and reversibly mounted on a shank and lprovided with peripherally dis-- posed cutting elements, said member having a centrally `disposed cylindrical bore extendingtherethrough 'and an enlarged central recess l tapered polygonal portion of the shank and anadjacent each end formed to provide a plurality of circumferentially spaced 'inwardly projecting longitudinally extending shoulders.

9. In a rotary cutting tool, the combination comprising: a shank having a portion formed to provide a'plurality of circumferentially spaced' outwardly; projecting longitudinally extendingshoulders; a vplurality of cutting members removsaid cutting members being provided with a plu-l rality of circumferentially spaced inwardly prothe forward end of the shank and a cylindrical portion of reduceddiameter extending forward from said polygonal portion; a driving sleeve fitting closelyandslidably aroundv the cylindrical portion ofthe shank and having an exterior surface of polygonal shape tapered inwardly from the middle toward each end thereof; two cutting members removably mounted lon said shank in successive positions longitudinallyvthereof, the rearward one of said cutting members havingra portion of polygonal internal shape adapted to t around and in driving engagement with .the

other portion of polygonal internal shape adaptedA to fit around and in driving engagement with the rearwardly tapered portion of said sleeve, and the forward one of said cutting members having a portion of polygonal rinternal shape ,adaptedto t around and in driving engagement with` the forwardly tapered portion of said sleeve; and

means removably secured to the shank and en- 

